Polyphenylquinoxalines are high temperature thermoplastics which exhibit excellent performance as adhesives, coatings, films and composite matrices. These materials are heterocyclic polymers synthesized by the condensation reaction of a bis(phenyl-.alpha.-diketone) with an aromatic bis(o-diamine).
Schematically, this may be represented in Equation I: ##STR1##
Polyphenylquinoxalines prepared from such condensations are configurationally unordered with three possible isomers distributed randomly along the polymer chain; see Hergenrother, Encyclopedia of Polymer Science Technology, Vol. 13, p. 55, (1988).
As a direct result of the use of the condensation reaction to synthesize polyphenylquinoxalines, there are several limitations.
First, because the polyphenylquinoxalines are not configurationally ordered, their mechanical properties (as evidenced for example by tensile modulus) and strength are limited, and the resultant lack of crystallinity renders them subject to attack by chlorinated organic solvents.
Second, the bis(phenyl-.alpha.-diketones) required for polyphenylquinoxaline formation are relatively difficult to prepare and expensive.
Third, the structure of polyphenylquinoxaline is difficult to vary.
Thus, it is an object of this invention to prepare configurationally ordered polyphenylquinoxalines, in order to improve strength and resistance to attack by organic solvents.
It is a further object to devise a means of preparing polyphenylquinoxaline, either configurationally ordered or not, by a means other than the bis(phenyl-.alpha.-diketone)/bis(o-diamine)condensation, so that the use of expensive bis(phenyl-.alpha.-diketones) may be avoided and so that the polyphenylquinoxaline structure can be more readily and conveniently varied.